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In this paper, an experimental study aiming at understanding the seismic behaviour of dry stone retaining walls is presented. Harmonic shaking table tests have been carried out on scaled-down dry-joint retaining walls involving parallelepiped bricks. It is found that a thicker wall is more resistant and that a given retaining wall is less sensitive to higher frequencies. For those higher frequencies, the walls accept larger displacements before collapsing. The displacements start to occur from a given threshold, which depends on the wall geometry but not on the frequency of the base motion. The typical toppling failure is observed for slender wall and/or low frequency inputs. For less slender walls or higher frequency inputs, walls experience local sliding failures until the complete collapse of the system. The acceleration at failure reported during the dynamic tests has been compared to the corresponding pseudo-static resistance, enabling a conservative estimate of the seismic behaviour coefficient for pseudo-static analysis of this class of retaining walls. This novel experimental dataset is aimed to serve as a validating framework for future numerical or analytical tools in the field. [ABSTRACT FROM AUTHOR]

In recent years, experimental techniques based on microdielectrometry have attracted increasing interest for continuous monitoring, in a nondestructive way, of the advancement of the reaction of thermoset resins under cure. The extension of this technique for 'in-situ' monitoring of the crystallization of thermoplastics has been carried out. A correlation between the evolution of the dielectric parameters of the material and its viscoelastic properties was done. A dynamic rheometer equipped with a dielectric cell and an instrumented slit die was designed. The clystallization process is depicted by a conductivity drop and by the occurrence of a maximum in the real permittivity. The decrease of the specific conductivity results from a modification of the conductive paths, whereas the increase of the permittivity is due to an interfacial polarization phenomenon (so-called Maxwell Wagner Sillars effect) between the amorphous phase and the growing crystalline entities. The sudden variation of the dielectric respon se is envisioned as a means for following the progression of the crystallization front within a mold. The description of the crystallization with Nakamura's model allowed the modeling of the crystallization inside a mold. The evolution of the temperature profile and of the crystallinity rate is modeled by a classical finite difference method. Dielectric measurements performed at controlled cooling rate experiments are in good agreement with the numerical simulation results and confirm the usefulness of dielectric measurements for 'in-situ' monitoring of the crystallization process of a polymer inside a mold., INTRODUCTION For about fifteen years, microdielectrometry has been applied to the monitoring of polymer network polymerization. This technique permits a nondestructive and in-situ characterization of the polymerization of a reactive [...]

Plant allometric relationships were studied at the end of the 1999–2000 growing season for eight grasses. Logarithmic regressions were developed relating above-ground biomass to dimensional measurements or to tiller density. Basal diameters (the longest and the greatest perpendicular to the first) and plant height (defined as that reached by vegetative tillers) were recorded on individual plants of tussock grasses. The number of tillers per 1 m2 plot was counted for a rhizomatous grass. Our study proved that regression models including basal area or a combination of basal area and height as independent variables gave a good fit to the biomass data for tussock grasses. Density of tillers proved to be a good predictor of biomass for a rhizomatous species. A validation test using 20% of the data not used for estimating the regression equations indicated that these models made accurate prediction of grass biomass. Further work is needed to prove if there are year-to-year differences between models. [Copyright &y& Elsevier]

Describes the application of microdielectrometry method for in situ monitoring of thermoplastic crystallization during an injection molding process. Decrease in the specific conductivity; Increase in permittivity; Analysis of dielectric properties during the filling, post-filling and cooling phase.